1. Field of the Invention
The present invention relates to a printing apparatus that performs processing for removing fingerprints left on a printing medium, and a method of controlling the same.
2. Description of the Related Art
Grease and moisture from the human body causes a reduction in resistivity in portions of a sheet that come into contact with a fixer, and there are cases where, for example, they cause a transfer failure when toner is transferred to the sheet, thus resulting in fingerprint marks being left on the printing result as shown by reference sign 1601 in FIG. 16. In order to address such a defect in a fixed image, there is known to be an image forming apparatus that has a fingerprint removal mode function for removing fingerprint marks by causing a sheet with fingerprints on it to pass through the fixer one time before printing in order to remove the oil component of the fingerprints on the sheet (Japanese Patent Laid-Open No. 2007-286108). Japanese Patent Laid-Open No. 2007-286108 discloses that the image forming apparatus removes smudging such as a fingerprint mark by executing pre-fixing on sheets fed to the manual paper feed tray. Japanese Patent Laid-Open No. 2007-286108 further discloses that a user can enable/disable the fingerprint removal function using an operation unit.
In Japanese Patent Laid-Open No. 2007-286108, the fingerprint removal mode is set using the operation unit of the image forming apparatus when printing sheets have been fed to the manual paper feed tray. For this reason, when the fingerprint removal mode is set, printing is performed in the fingerprint removal mode until all of the sheets set in the manual paper feed tray are gone. Since the fingerprint removal mode involves operations in which printed matter is passed through the fixer one time before being printed on and then discharged, the printing speed is slower than that in normal printing.
Fingerprints left on a sheet actually gradually disappear as time passes. Although it depends on the type and thickness of the printing sheet, fingerprints on ordinary copy sheets disappear in approximately 30 minutes. Accordingly, there are cases where fingerprint removal does not need to be performed for printing sheets for which a long time has passed since being stored in the paper feed tray. Performing fingerprint removal in such case results in an unnecessary increase in the printing time.